Antiparasitic avermectin and milbemycin derivatives

ABSTRACT

Avermectin and milbemycin derivatives of formula (I) ##STR1## having a double bond at the 3-4 position and a cyano substituent at the 3-position have outstanding anthelmintic properties. They may be prepared by allowing an avermectin or milbemycin derivative having a leaving group at the 5-position, or having double bonds at the 2-3 and 4-5 positions and no substituent at the 5-position, to react with an ionic cyanide.

This application is a 371 of PCT/EP93/00423 filed Feb. 23, 1993.

This application is a 371 of PCT/EP93/00423 filed Feb. 23, 1993,published as WO93/18041 Sep. 16, 1993.

This invention relates to antiparasitic agents and in particular tocompounds related to the avermectins and milbemycins but having a cyanosubstituent at the 3-position and lacking a substituent at the5-position.

The avermectins are a group of broad-spectrum antiparasitic agentsreferred to previously as the C-076 compounds. They are produced byfermenting a certain strain of microorganism Streptomyces avermitilis inan aqueous nutrient medium. The preparation and structure of thesecompounds obtained by fermentation are described in British PatentSpecification 1573955. The milbemycins are structurally relatedmacrolide antibiotics lacking the sugar residues at the 13-position.They may be produced by fermentation, for example as described inBritish Patent Specification No. 1390336 and European PatentSpecification No. 0170006.

In addition to these fermentation-derived products, a large number ofpublications describe compounds derived semisynthetically from theseproducts, many of which possess useful antiparasitic properties. Some ofthis chemistry is reviewed in Macrolide Antibiotics, Omura S., Ed.,Academic Press, New York (1984) and by Davies, H. G. and Green, R. H. inNatural Product Reports (1986), 3, 87-121 and in Chem. Soc. Rev. (1991),20, 211-269 and 271-239.

Compounds related to the original C-076 avermectins have also beenprepared by fermentation of avermectin-producing micro-organisms. Forexample European Patent Specifications 0214731 and 0317148 describeproduction of compounds related to the C-076 avermectins but having adifferent substituent at the 25-position by fermentation in thepresence, in the fermentation medium, of certain acids.

Other publications mentioning different combinations of substituents atvarious positions on the avermectin or milbemycin nucleus areEP-A-317148, 340932, 335541, 350187, 410615, 259779 and 254583;DE-A-2329486 and GB-A-2166436.

The avermectins and milbemycins and their derivatives have thestructure: ##STR2## wherein the broken line represents an optional bond,R¹ and R⁴ being absent when this bond is present, R¹, R³, R⁴ and R¹² areindependently H, OH, halo, oxo, oximino or an organic radical, R² and R⁷are organic radicals, R⁶ is H or an organic radical.

These compounds include the avermectins themselves and their substitutedderivatives in which R³ is a 4'-(α-L-oleandrosyl)-α-L-oleandrosyloxygroup, optionally substituted at the 4" position; the avermectinmonosaccharides and their derivatives in which R³ is α-L-oleandrosyloxy,optionally substituted at the 4' position; the avermectin aglycones andtheir derivatives in which R³ is OH or a substituent other thanoleandrosyl replacing this group; and the milbemycins and theirderivatives in which R³ is H.

All the avermectins and structurally related milbemycins and theirderivatives hitherto known have no substituent at the 3-position with aC3-C4 double bond, neither has any process capable of producing suchcompounds been reported.

It has now been discovered that avermectin and milbemycin derivativeshaving a cyano substituent at the 3-position, with no substituent at the5-position, may be prepared and that some of these compounds haveoutstanding antiparasitic properties.

According to one aspect of the invention, there are provided avermectinand milbemycin derivatives having a cyano substituent at the 3-position,a double bond between the 3-4 positions and no substituent at the5-position of the molecule.

Compounds of the invention are of formula (I): ##STR3## wherein thebroken line represents an optional bond, R¹ and R⁴ being absent whenthis bond is present, R¹, R³, R⁴ are independently H, OH, halo, oxo,oximino, or an organic radical, and R² and R⁷ are organic radicals andR⁶ is H or an organic radical.

Compounds according to the invention include those in which the 22-23optional bond is present and those in which this optional bond is absent(i.e. a single bond between the 22 and 23 positions); R¹ is H, OH, C₁-C₈ alkoxy optionally substituted by halo or by C₁ -C₄ alkoxy, C₂ -C₅alkanoyl, C₂ -C₅ alkoxy carbonyl, carboxy, mercapto or by aryl, or R¹ isC₃ -C₈ alkenyloxy, C₂ -C₉ alkylcarbonyloxy or C₃ -C₉ alkenylcarbonyloxy,arylcarbonyl or carbamoyl optionally substituted by a C₁ -C₉ alkylgroup, or R¹ is attached to the remainder of the molecule by a doublebond and is oxo or oximino optionally O-substituted by a C₁ -C₈ alkyl,alkenyl, alkynyl, trialkylsilyl or aralkyl group, or is methyleneoptionally substituted by a cyano or C₁ -C₉ alkyl group;

R⁴ is H, OH or C₁ -C₈ alkoxy or C₁ -C₉ alkanoyloxy, or is attached tothe remainder of the molecule by a double bond and is ═CH₂, oxo oroximino optionally substituted as above;

R² is

(a) an alpha-branched C₃ -C₈ , alkyl, alkenyl (including but-2-enyl,pent-2-enyl, and 4-methylpent-2-enyl), alkoxy-alkyl, or alkylthioalkylgroup; an alpha-branched C4-C₈ alkynyl group; a (C₄ -C₈)cycloalkyl-alkylgroup wherein the alkyl group is an alpha-branched C₂ -C₅ alkyl group; aC₃ -C₈ cycloalkyl or C₅ -C₈ cycloalkenyl group, either of which mayoptionally be substituted by methylene or one or more C₁ -C₄ alkylgroups or halo atoms; or a 3 to 6 membered oxygen or sulphur containingheterocyclic ring which may be saturated, or fully or partiallyunsaturated and which may optionally be substituted by one or more C₁-C₄ alkyl groups or halo atoms; or

(b) a group of the formula --CH₂ R⁸ wherein R⁸ is H, C₁ -C₈ alkyl, C₂-C₈ alkenyl, C₂ -C₈ alkynyl, alkoxyalkyl or alkylthioalkyl containingfrom 1 to 6 carbon atoms in each alkyl or alkoxy group, wherein any ofsaid alkyl, alkoxy, alkenyl or alkynyl groups may be substituted by oneor more halo atoms; or a C₃ -C₈ cycloalkyl or C₅ -C₈ cycloalkenyl group,either of which may optionally be substituted by methylene or one ormore C₁ -C₄ alkyl groups or halo atoms; or a 3 to 6 membered oxygen orsulphur containing heterocyclic ring which may be saturated, orpartially unsaturated and which may optionally be substituted by one ormore C₁ -C₄ alkyl groups or halo atoms; or a group of the formula SR⁹wherein R⁹ is C₁ -C₈ alkyl, C₂ -C₈ alkenyl, C₃ -C₈ alkynyl, C₃ -C₈cycloalkyl, C₅ -C₈ cycloalkenyl, phenyl or substituted phenyl whereinthe substituent is C₁ -C₄ alkyl, C₁ -C₄ alkoxy or halo; or a 3 to 6membered oxygen or sulphur containing heterocylic ring which may besaturated, or fully or partially unsaturated and which may optionally besubstituted by one or more C₁ -C₄ alkyl groups or halo atoms; or

(c) a C₁ -C₆ alkyl group substituted by one oxo or one or more hydroxygroups or by a single oxygen atom on two adjacent carbon atoms formingan oxirane ring, or R² is a C₁ -C₅ alkyl group substituted by a (C₁ -C₆)alkoxy-carbonyl group, said substituents on R₂ being attached to eitheror both of a terminal carbon atom and a carbon atom adjacent a terminalcarbon atom of R² ; or

(d) ═CH₂ or a group of the formula: ##STR4## wherein R¹⁰ and R¹¹ areboth H; R¹⁰ is H and R¹¹ is C₁ -C₃ alkyl, or one of R¹⁰ and R¹¹ is H andthe other is phenyl, heteroaryl, C₂ -C₆ alkoxycarbonyl or substitutedphenyl or heteroaryl wherein said substituent is fluorine, chlorine, C₁-C₄ alkyl, C₁ -C₄ alkoxy, C₁ -C₄ alkylthio, hydroxy(C₁ -C₄)alkyl, cyano,aminosulphonyl, C₂ -C₆ alkanoyl, C₂ -C₆ alkoxycarbonyl, nitro,trifluoromethyl, trifluoromethoxy, amino or mono or di(C₁ -C₄)alkylamino; and X is a direct bond or is an alkylene group having from 2to 6 carbon atoms which may be straight or branched-chain; or

(e) phenyl which may optionally be substituted with at least onesubstituent selected from C₁ -C₄ alkyl, C₁ -C₄ alkylthio groups, haloatoms, trifluoromethyl, and cyano;

or R² may be a group of formula (II): ##STR5## wherein Z is O, S or--CH₂ -- and a, b, c and d may each independently be 0, 1 or 2; the sumof a, b, c, and d not exceeding 5;

R³ is hydrogen, hydroxy, C₁ -C₈ alkoxy or alkenoxy, C₁ -C₉ alkanoyloxyor alkenoyloxy, aroyloxy, oxymethyleneoxy-(C₁ -C₅)alkyloxy-(C₁-C₅)alkyl, halogen, oxo, or optionally substituted oximino, hydrazono,carbazido or semicarbazido, N-(C₁ -C₄)alkyl semicarbazido, N,N-di(C₁-C₄)alkylsemicarbazido, C₁ -C₅ alkanoylhydrazido, benzoylhydrazido or(C₁ -C₄)alkyl benzoylhydrazido; or R₃ is ##STR6## wherein R⁵ is attachedto C-4" or C-4' by a single bond and is hydrogen, halo, hydroxy, C₁ -C₉alkanoyloxy or alkenoyloxy, aroyloxy, C₁ -C₈ alkoxy, amino, N-(C₁ -C₈)alkylamino, N,N-di(C₁ -C₉) alkylamino, N-(C₁ -C₅)alkanoylamino, orN,N-di(C₁ -C₉) alkanoylamino; or R⁵ is attached to C-4" or C-4' by adouble bond and is oxo, optionally substituted oximino, semicarbazido,N-(C₁ -C₄) alkylsemicarbazido, N,N-di(C₁ -C₄)alkylsemicarbazido, (C₁-C₅) alkanoylhydrazido, benzoylhydrazido, or (C₁-C₄)alkylbenzoylhydrazido; R₆ is H or C₁ -C₆ alkyl;

and R₇ is methyl, hydroxymethyl, (C₁ -C₄ alkoxy)methyl, (C₂ -C₅alkanoyl) oxymethyl, (C₂ -C₅ alkenoyl)oxymethyl, aroyloxymethyl,aralkanoyloxymethyl, oxo, optionally substituted oximino, halomethyl,azidomethyl or cyanomethyl.

Compounds of the invention include those in which R¹ is H, OH, O-(C,₁-C₄)alkyl, O-(C₁ -C₅)alkanoyl, oxo and oximino optionally substituted byC₁ -C₄ alkyl or aryl(C₁ -C₄)alkyl; those in which R² is straight orbranched-chain alkyl, alkenyl, cycloalkyl or cycloalkenyl (includingmethyl, ethyl, 2-propyl, 2-butyl, 2-buten-2-yl, 2-penten-2-yl,4-methyl-2-penten-2-yl and cyclohexyl); those in which R⁴ is H, OH, oxoor oximino; and those in which R³ is H or is of formula: ##STR7## whereR⁵ is OH, (C₁ -C₄) alkoxy, (C₂ -C₅) alkanoyloxy, amino, N-(C₁ -C₄)alkylamino, N-(C₁ -C₅)alkanoylamino, oxo or oximino optionallysubstituted by a C₁ -C₄ alkyl group.

In all the above definitions, unless the context requires otherwise,alkyl groups containing 3 or more carbon atoms may be straight orbranched-chain; halo means fluoro, chloro, bromo or iodo; and aryl meansphenyl optionally substituted by one or more C₁ -C₄ alkyl or C₁ -C₄alkoxy groups or halo atoms.

Compounds within the scope of the invention include:

(i) 3-cyano-5-deoxy-25-cyclohexyl avermectin B2 or its monosaccharide,or

(ii) 3-cyano-5-deoxy-23-methoxy-25-cyclohexyl-22,23-dihydroavermectin B1or its monosaccharide, or

(iii)4"-oximino-3-cyano-5-deoxy-23-methoxy-25-cyclohexyl-22,23-dihydroavermectinB1; or

(iv) 3-cyano-5-deoxy-25-cyclohexyl-22,23-dihydroavermectin B1 or itsmonosaccharide, or

(v) 4,-epi-hydroxy-3-cyano-5-deoxy-25-cyclohexyl-22,23-dihydroavermectinB1 monosaccharide, or

(vi)23-methoximino-3-cyano-5-deoxy-25-cyclohexyl-22,23-dihydroavermectin B1or its monosaccharide; or

(vii) 3-cyano-5-deoxy-25-cyclohexylavermectin B1 or its monosaccharide;or

(viii)3-cyano-5,13-dideoxy-23-methoxy-25-cyclohexyl-22,23-dihydroavermectin B1aglycone; or

(ix) 3-cyano-5,13-dideoxy-25-cyclohexyl-22,23-dihydro avermectin B1aglycone; or

(x) 3-cyano-5-deoxy-milbemycin D.

The avermectins and monosaccharides are generally preferred over theaglycones and milbemycins and their derivatives having no saccharidegroups at the 13-position.

It will be understood that the compounds of the invention includeseveral asymmetric centres and accordingly may exist as several pairs ofstereoisomers. The invention includes all such stereoisomers, whetherseparated or not.

A further aspect of the invention provides a method of making such anavermectin or milbemycin derivative which comprises allowing anavermectin or milbemycin derivative substituted at the 5-position with aleaving radical, or having no substituent at the 5-position and doublebonds at the 2-3 and 4-5 positions, to react with an ionic cyanide.

Derivatives having double bonds at the 2-3 and 4-5 positions are offormula (II): ##STR8## where R¹, R², R³, R⁴, R⁶ and R⁷ are as definedabove. The compounds of the formula (II) are themselves novel.

The compound of formula (II) may be prepared from a compound of formula(III): ##STR9## where R¹, R², R³, R⁴, R⁶ and R⁷ are as defined above andX is a leaving group such as fluoro, chloro, bromo, iodo, phenoxyoptionally substituted with at least one electron-withdrawing group suchas p-nitro, and sulphonic acid groups such as methanesulphonyloxy andp-toluenesulphonyloxy. Elimination of the leaving group at the5-position results in formation of the compound of formula (II) andaddition of cyanide thereto gives a compound of formula (I), the cyanogroup being attached to the nucleus of the molecule at the 3-position.It has been found that isolation of the intermediate compound of formula(II) is not generally necessary. Thus, treatment of the compound (III)with an ionic cyanide such as lithium cyanide in a non-aqueous solventsuch as dimethylformamide results in elimination of the leaving groupand formation of compound (I) in a single reaction step. The reactionmay generally be conducted at room temperature. The compound of formula(I) may be isolated from the reaction mixture and purified byconventional methods, for example by solvent extraction followed bychromatography.

Compound (III) in which X is a leaving group may be prepared from thecorresponding compounds in which X is OH by conventional methods, forexample by treating the 5-OH compound with e.g. 2-nitrobenzenesulphonylchloride in a basic solvent such as pyridine to form the 5-Cl compound.The product of formula (III) may be isolated from the reaction mixtureby conventional methods.

It has been found that, when the leaving group is, for example,p-nitrophenoxy, the intermediate compound (III) need not be isolated andthe compound of formula (I) may be prepared, from the compound in whichX is OH, by a "one-pot" process in which the starting compound isconverted to the p-nitrophenoxy derivative which is then treated withthe cyanide while still in the original reaction solution.

The starting materials of formula (III) in which X is OH, comprisingdifferent combinations of substituents R¹ -R⁷, may generally be made bymethods known in the art and discussed in the above-mentionedpublications. It is believed that the above-described method of theinvention is applicable to all compounds of formula (III) in whichsubstituents R¹ -R⁷ are compatible with the reagents used. However insome instances it may be necessary or desirable to replace some of theR¹ -R⁷ substituents with other substituents after conversion of theformula (III) starting material to the 3-cyano compound. Suchconversions may also be carried out by methods known in the art and asdescribed in the published patent documents and other documents hereinmentioned.

As previously mentioned the compounds of the invention are highly activeantiparasitic agents. Thus the compounds are effective in treating avariety of conditions caused by endoparasites including, in particular,helminthiasis which is most frequently caused by a group of parasiticworms described as nematodes and which can cause severe economic lossesin swine, sheep, horses and cattle as well as affecting domestic animalsand poultry. The compounds are also effective against other nematodeswhich affect various species of animals including, for example,Dirofilaria in dogs and various parasites which can infect animals andhumans including gastro-intestinal parasites such as Ancylostoma,Necator, Ascaris, Strongyloides, Trichinella, Toxocara, Capillaria,Trichuris, Enterobius and parasites which are found in the blood orother tissues and organs such as filiarial worms and theextra-intestinal stages of Strongyloides, Trichinella and Toxocara.

The compounds are also of value in treating ectoparasite infectionsincluding in particular arthropod ectoparasites of humans, animals andbirds such as ticks, mites, lice, fleas, blowfly, biting insects andmigrating dipterous larvae which can affect cattle and horses.

The compounds of formula (I) may be administered as a formulationappropriate to the specific use envisaged and to the particular speciesof host animal being treated and the parasite or insect involved. Foruse as an anthelmintic the compounds may be administered by injection,either subcutaneously or intramuscularly, alternatively they may beadministered orally in the form of a capsule, bolus, tablet, chewabletablet or liquid drench, or they may be administered as a topicalformulation or as an implant. For topical application dip, spray,powder, dust, pour-on, spot-on, jetting fluid, shampoos, collar, tag orharness may be used. Such formulations are prepared in a conventionalmanner in accordance with standard veterinary practice. Thus capsules,boluses or tablets may be prepared by mixing the active ingredient witha suitable finely divided diluent or carrier, additionally containing adisintegrating agent and/or binder such as starch, lactose, talc, ormagnesium stearate. A drench formulation may be prepared by dispersingthe active ingredient in an aqueous solution together with dispersing orwetting agents and injectable formulations may be prepared in the formof a sterile solution or emulsion. Pour-on or spot-on formulations maybe prepared by dissolving the active ingredient in an acceptable liquidcarrier vehicle, such as butyl digol, liquid paraffin or non-volatileester with or without addition of a volatile component such asisopropanol. Alternatively, pour-on, spot-on or spray formulations canbe prepared by encapsulation to leave a residue of active agent on thesurface of the animal. These formulations will vary with regard to theweight of active compound depending on the species of host animal to betreated, the severity and type of infection and the body weight of thehost. The compounds may be administered continuously, particularly forprophylaxis, by known methods. Generally for oral, parenteral andpour-on administration a dose of from about 0.001 to 10 mg per kg ofanimal body weight given as a single dose or in divided doses for aperiod of from 1 to 5 days will be satisfactory but of course there canbe instances where higher or lower dosage ranges are indicated and suchare within the scope of this invention.

As an alternative the compounds may be administered with the animalfeedstuff and for this purpose a concentrated feed additive or premixmay be prepared for mixing with the normal animal feed.

For use as an insecticide and for treating agricultural pests thecompounds are applied as sprays, dusts, pour-on formulations, emulsionsand the like in accordance with standard agricultural practice.

For human use the compounds are administered as a pharmaceuticallyacceptable formulation in accordance with normal medical practice.

The compounds are also useful against insect pests of stored grains suchas Tribolium sp., Tenebrio sp., and of agricultural plants such asspider mites, (Tetranychus sp.) aphids, (Acyrthiosiphon sp.), againstmigratory orthopterans such as locusts and immature stages of insectsliving on plant tissue. The compounds are useful as nematocides for thecontrol of soil nematodes and plant parasites such as Meloidogyne sp.which may be of importance in agriculture. The compounds are activeagainst other plant pests such as the southern army worm and Mexicanbean beetle larvae.

For use as insecticides the compounds are applied as sprays, dusts,emulsions, pour-on formulation and the like in accordance with standardveterinary practice.

The invention is illustrated by the following Examples, in which"avermectin B2" refers to an avermectin having an OH substituent at the23 position and a single bond at the 22-23 position, and "avermectin B1"refers to an avermectin having a double bond at the 22-23 position.

EXAMPLE 1 5-Chloro-5-deoxy-25-cyclohexlavermectin B2

To a solution of 25-cyclohexylavermectin B2 (20 g), obtained asdescribed in EP-A-214731, in pyridine (100 ml) maintained at 0° C. wasadded, portionwise, over a period of 30 minutes, 2-nitrobenzenesulphonylchloride (45 g). The reaction mixture was stirred for 1 hour duringwhich time it was allowed to warm to room temperature. It was thenpoured into ethyl acetate (1000 ml) and aqueous hydrochloric acid (500ml, 1N). The organic layer was separated, dried (MgSO₄) and evaporatedto give an oil which was taken up in dichloromethane (100 ml) andapplied to a column of silica gel (1 Kg). Elution with dichloromethane:methanol--100:0 to 95:5--afforded, following combination and evaporationof suitable fractions, the title compound (12 g) which was characterisedby mass and nmr spectroscopy.

EXAMPLE 2 3-Cyano-5-deoxy-25-cyclohexylavermectin B2

To a solution of 5-chloro-5-deoxy-25-cyclohexylavermectin B2 (20 g) fromExample 1 in dimethylformamide (200 ml) was added a solution of lithiumcyanide in dimethylformamide (200 ml, 0.5M). The mixture was stirred atroom temperature for 24 hours. The reaction mixture was poured intowater (750 ml) and ether (1500 ml). The organic layer was separated,washed with water (500 ml, ×2) and brine (500 ml), then dried (MgSO₄)and evaporated to yield an oil (25 g). The oil was taken up in ether (50ml) and applied to a column of silica gel (1Kg). Elution with ethergave, after combination and evaporation of appropriate fractions, awhite powder (5.1 g). This was further purified by reverse-phase highperformance liquid chromatography on a Dynamax (trade mark) 2" diameterODS C18 column eluting with methanol:water 80:20. Combination andevaporation of appropriate fractions gave a white, amorphous powder(2.38 g) which was further purified by reverse-phase high performanceliquid chromatography on a Dynamax (trade mark) 2" diameter ODS Cl8column eluting with acetonitrile:methanol:water 65:5:30. Combination andevaporation of appropriate fractions gave the title compound as a white,amorphous powder which was characterised by mass and nmr spectroscopy.

EXAMPLES 3 and 4 3-Cyano-5-deoxy-25-cyclohexylavermectin B2monosaccharide and 3-cyano,5-deoxy-25-cyclohexylavermectin B2 aglycone

3-Cyano-5-deoxy-25-cyclohexylavermectin B2 (290 mg) from Example 2 wasdissolved in isopropanol containing 1% of sulphuric acid (6 ml) and thesolution left at room temperature for 24 hours. The reaction mixture wasthen poured onto ice (15 g) and water (15 ml) and extracted withdichloromethane (20 ml, ×2). The combined organic extracts were washedwith aqueous potassium hydrogen carbonate solution, dried (Na₂ SO₄) andevaporated to yield an off-white solid (280 mg). This was purified byreverse-phase high performance liquid chromatography on a Dynamax (trademark) 2" diameter ODS C18 column eluting withacetonitrile:methanol:water (57:13:30). Combination and evaporation ofappropriate fractions gave the title monosaccharide (105 mg) andaglycone (7 mg) as amorphous, white powders which were characterised bymass and nmr spectroscopy.

EXAMPLE 5 5-Chloro-5-deoxy-23-methoxy-25-cyclohexyl-22,23-dihydroavermectin B1

To a solution of 23-methoxy-25-cyclohexyl-22,23-dihydroavermectin B1 (50g) as described in International Patent Application PCT/EP93/0036 inpyridine (250 ml) at 0° C. was added ortho-nitrobenzenesulphonylchloride (25 g) and the mixture was stirred for 1 hour during which timeit was allowed to warm to room temperature. The reaction mixture waspartitioned between ethyl acetate (1000 ml) and aqueous hydrochloricacid (500ml, 1N). The organic phase was separated, washed with water(250 ml, ×2), dried (MgSO₄) and evaporated. The crude product was takenup in dichloromethane and applied to a column of silica gel (1Kg).Elution with dichloromethane:methanol--100:0 to 99:1--afforded,following combination and evaporation of suitable fractions, the titlecompound (55 g) which was characterised by mass and nmr spectroscopy.

EXAMPLE 63-Cyano-5-deoxy-23-methoxy-25-cyclohexyl-22,23-dihydroavermectin B1

To a solution of5-chloro-5-deoxy-23-methoxy-25-cyclohexyl-22,23-dihydroavermectin B1(10.1 g) in dimethylformamide (55 ml) was added a solution of lithiumcyanide in dimethylformamide (55 ml, 0.5M). The mixture was stirred atroom temperature for 24 hours. The reaction mixture was then poured intoether (500 ml) and water (250 ml). The organic layer was separated. Theaqueous layer was extracted with ether (250 ml, ×2).

The combined organic layers were then washed with water (250 ml), thensaturated aqueous sodium chloride solution (250 ml), dried (MgSO₄) andevaporated to give a yellow foam (8.4 g). This was taken up in theminimum volume of ether and applied to a column of silica gel (1 Kg).Elution with ether:hexane--2:1 to 4:1--gave, after combination andevaporation of appropriate fractions, a white powder (2 g). This wasfurther purified by reverse-phase high performance liquid chromatographyon a Dynamax (trade mark) 2" diameter ODS C18 column eluding withwater:methanol:acetonitrile--15:20:65. Combination and evaporation ofappropriate fractions gave the title compound as a white, amorphouspowder which was characterised by mass and nmr spectroscopy.

EXAMPLES 7 and 83-Cyano-5-deoxy-23-methoxy-25-cyclohexyl-22,23-dihydroavermectin B1monosaccharide and3-cyano-5-deoxy-23-methoxy-25-cyclohexyl-22,23-dihydroavermectin B1aglycone

3-Cyano-5-deoxy-23-methoxy-25-cyclohexyl-22,23-dihydroavermectin B1 (285mg) was dissolved in isopropanol containing 1% of sulphuric acid (6 ml)and the solution was left at room temperature for 24 hours. The reactionmixture was then poured onto ice (15 g) and water (15 ml) and extractedwith dichloromethane (20 ml, ×2). The combined organic extracts werewashed with aqueous potassium hydrogen carbonate solution, dried (MgSO₄)and evaporated to yield a white solid (280 mg). This was purified byreverse-phase high performance liquid chromatography on a Dynamax (trademark) 2" diameter ODS C18 column eluted at 45 ml/min withwater:methanol: acetonitrile--20:15:65 for 36 mins, then 18:17:65.Fractions were collected between 26 and 30 minutes and between 42 and 54minutes. Combination and evaporation of appropriate fractions gave thetitle monosaccharide (65 mg) and aglycone (3 mg) as amorphous, whitepowders which were characterised by mass and nmr spectroscopy.

EXAMPLE 94"-oxo-3-cyano-5-deoxy-23-methoxy-25-cyclohexyl22,23-dihydroavermectinB1

A mixture of3-cyano-5-deoxy-23-methoxy-25-cyclohexyl-22,23-dihydro-avermectin B1(560 mg), tetra-npropylammonium perruthenate (56 mg), N-methylmorpholineoxide (560 mgs) and dichloromethane (15 ml) was stirred overnight.Further N-methylmorpholine-N-oxide (100 mg) and tetra-n-propylammoniumperruthenate (10 mg) were added and stirring continued overnight. Themixture was added to a silica column (50 g). The column was eluted withdichloromethane:ethyl acetate--100:0 to 80:20. Combination andevaporation of appropriate fractions gave the title compound (410 mg)which was characterised by mass and nmr spectroscopy.

EXAMPLE 10 (E andZ]-4"-Oximino-3-cyano-5-deoxy-23-methoxy-25-cyclohexyl-22,23-dihydroavermectinB1

A mixture of4"-oxo-3-cyano-5-deoxy-23-methoxy-25-cyclohexyl-22,23-dihydroavermectinB1 (510 mg), hydroxylamine hydrochloride (500 mg) and pyridine (10 ml)was stirred at room temperature overnight. The reaction mixture waspoured into water (50 ml) and extracted with ether (50 ml, ×2). Thecombined organic layers were washed with aqueous citric acid (25 ml,10%), water (25 ml), dried (MgSO₄) and evaporated to give the crudeoximes (500 mg). The crude product was purified by reverse-phase highperformance liquid chromatography on a Dynamax (trade mark) 2" diameterODS C18 column eluted at 45 ml/min with water:methanol:acetonitrile30:5:65 for 44 minutes, then 28:7:65 for 12 minutes, then 26:7:65 for 4minutes, then 25:10:65 for 16 minutes, then 20:15:65 for 9 minutes, then15:20:65 for 41 minutes. Fractions were collected between 92 and 116minutes. Combination and evaporation of appropriate fractions gave awhite powder (290 mg) which was further purified by reverse-phase highperformance liquid chromatography on a Dynamax (trade mark) 2" diameterODS C18 column eluted at 45 ml/min withwater:methanol:acetonitrile--25:10:65 for 72 minutes, then 15:20:65 for28 minutes. Fractions were collected between 72 and 100 minutes.Combination and evaporation of appropriate fractions gave the titlecompounds as a white powder which were characterised by mass and nmrspectroscopy.

EXAMPLE 1113-Chloro-13-deoxy-3-cyano-5-deoxy-23-methoxy-25-cyclohexy-1-22,23-dihydroavermectinB1 aglycone

To a stirred solution of3-cyano-5-deoxy-23-methoxy-25-cyclohexyl-22,23-dihydroavermectin B1aglycone (300 mg) in dichloromethane (10 ml) at 0° C containing4-dimethylaminopyridine (230 mg) and di-isopropylethylamine (0.33 ml)was added a solution of 2-nitrobenzenesulphonylchloride (240 mg) indichloromethane (3 ml). The reaction mixture was allowed to warm to roomtemperature and stirred overnight. The mixture was poured onto ice (15g) and water (15 ml), acidified with aqueous citric acid (10%) andextracted with dichloromethane (20 ml, ×2). The combined organic layerswere extracted with aqueous potassium hydrogen carbonate solution (20ml), dried (Na₂ SO₄) and evaporated to give an orange foam (360 mg).This was purified by column chromatography on silica gel (20 g) elutedwith dichloromethane:ethyl acetate--100:0 to 95:5. Combination ofappropriate fractions gave 80 mg of material which was further purifiedby reverse-phase high performance liquid chromatography on a Dynamax(trade mark) 1" column eluted with water:methanol--15:85. Combination ofappropriate fractions gave 50 mg of compound which was further purifiedunder the same conditions to 13 mg of material which was chromatographedon a silica gel (5 g) column eluted with dichloromethane: ethyl acetate100:0 to 98:2. Combination of appropriate fractions gave the titlecompound (10 mg) as white powder which was characterised by mass and nmrspectroscopy.

EXAMPLE 123-Cyano-5,13-dideoxy-23-methoxy-25-cyclohexyl-22,23-dihydroavermectin B1aglycone

To a solution of13-deoxy-23-methoxy-25-cyclohexyl-22,23-dihydroavermectin B1 aglycone(1.2 g) in dry pyridine (10 ml) was added 2-nitrobenzenesulphonylchloride (1 g) and the mixture was maintained at room temperature for 1hour. The solvent was then removed and the residue partitioned betweenether (50 ml) and hydrochloric acid (50 ml, 5%). The organic layer wasseparated, washed with water, then brine, and then dried (MgSO₄) andevaporated to give 980 mg of a gum. This was taken up indimethylformamide (8 ml) and a solution of lithium cyanide indimethylformamide added (8 ml, 0.5M). The reaction mixture was allowedto stand for 24 hours then poured into ether (16 ml) and water (16 ml).The layers were separated. The aqueous layer was extracted with ether(16 ml, ×3). The combined organic layers were washed with brine (20 ml,saturated), dried (MgSO₄) and evaporated to give a dark oil (0.91 g).The oil was taken up in ether and filtered through a plug of silica gelusing further volumes of ether to elute the product. Evaporation gave apale yellow foam (0.6 g). This was further purified by columnchromatography on silica gel (100 g) eluted with hexane:ether --9:1 to3:1. Combination and evaporation of appropriate fractions gave a whitefoam (110 mg). This was taken up in the minimum volume of methanol fromwhich a white solid was deposited. This was filtered off and dried toyield the title compound (47 mg) which was characterised by mass and nmrspectroscopy.

EXAMPLE 13 3-Cyano-5-deoxy-23-ethoxy-5-cyclohexyl-22,23-hydroavermectinB1

A solution of 3-cyano-5-deoxy-25-cyclohexylavermectin B2 (350 mg) inether (30 ml) containing ethyl iodide (1.75 ml) and a suspension ofsilver salicylate (1.4 g) was stirred at room temperature in the darkfor 24 hours. The mixture was filtered and evaporated to give an oil(1.5 g) which was purified by reverse-phase high performance liquidchromatography on a Dynamax (trade mark) 2" diameter ODS C18 columneluted with a mixture of water:methanol--10:90. Combination andevaporation of appropriate fractions gave the title compound as a whitesolid (150 mg) which was characterised by mass and nmr spectroscopy.

EXAMPLE 143-Cyano-5-deoxy-23-ethoxy-25-cyclohexyl-22,23-dihydroavermectin B1monosaccharide Method A

A solution of3-cyano-5-deoxy-23-ethoxy-25-cyclohexyl-22,23-dihydroavermectin B1 (45mg) in isopropanol containing 1% of sulphuric acid (1 ml) was maintainedat room temperature for 24 hours. The mixture was diluted with ether (20ml), washed with saturated aqueous sodium hydrogen carbonate solution(20 ml), water (20 ml), dried (MgSO₄) and evaporated.

Method B

A solution of 3-cyano-5-deoxy-25-cyclohexyl-22,23-dihydro-avermectin B2monosaccharide (120 mg) in ether (20 ml) containing ethyl iodide (0.5ml) and a suspension of silver salicyclate (0.5 g) was stirred at roomtemperature in the dark for 24 hrs. A further 0.2 g of silver salicylateand 0.2 ml of ethyl iodide were then added and stirring continued for afurther 72 hours. The mixture was filtered and evaporated.

The crude products from the above methods were combined and purified byreverse-phase high performance liquid chromatography on a Dynamax (trademark) 2" diameter ODS C18 column eluted with water:methanol--15:85.Combination and evaporation of appropriate fractions gave the titlecompound as a white solid (120 mg) which was characterised by mass andnmr spectroscopy.

EXAMPLE 15 5-Chloro-5-deoxy-25-cyclohexyl-22,23-dihydroavermectin B1

To a solution of 25-cyclohexyl-22,23-dihydroavermectin B1 (8.1 g) asdescribed in U.S. Pat. No. 5,089,480 in pyridine (40 ml) at 0° C. wasadded 2-nitrobenzenesulphonyl chloride (6 g). The mixture was stirredfor 2 hours during which time it was allowed to warm to roomtemperature. The reaction mixture was poured into water (250 ml) andextracted with ethyl acetate (250 ml, ×2). The combined organic layerswere washed with dilute aqueous hydrochloric acid, dilute aqueous sodiumhydrogen carbonate solution and water. After drying (MgSO₄) evaporationof the solvents gave the title compound as a yellow foam (6.5 g) whichwas characterised by mass and nmr spectroscopy.

EXAMPLE 16 3-Cyano-5-deoxy-25-cyclohexyl-22,23-dihydroavermectin B1

To a solution of 5-chloro-5-deoxy-25-cyclohexyl-22,23-dihydroavermectinB1 (8.2 g) in dimethylformamide (45 ml) was added a solution of lithiumcyanide in dimethylformamide (45 ml, 0.5M). The mixture was stirred atroom temperature for 24 hours. The work-up and open columnchromatographic procedures described in Example 6 were employed to givea white powder (2 g). 500 mg of this material were further purified byreverse-phase high performance liquid chromatography on a Dynamax (trademark) 2" diameter ODS C18 column eluted with a mixture ofwater:methanol:acetonitrile--5:30:65. Combination and evaporation ofappropriate fractions gave the title compound as a white solid which wascharacterised by mass and nmr spectroscopy.

EXAMPLES 17 and 18 3-Cyano-5-deoxy-25-Cyclohexy1-22,23-dihydroavermectinB1 monosaccharide and3-cyano-5-deoxy-25-cyclohexy1-22,23-dihydroavermectin B1 aglycone

A solution of 3-cyano-5-deoxy-25-cyclohexyl-22,23-dihydroavermectin B1(330 mg) in isopropanol containing 1% of sulphuric acid (7 ml) wasmaintained at room temperature for 24 hours. The mixture was poured ontoice (15 g) and water (15 ml) and extracted with dichloromethane (20 ml,×2). The combined organic layers were washed with water (20 ml), dried(MgSO₄) and evaporated to give a gum (330 mg) which was purified byreverse phase high performance liquid chromatography on a Dynamax (trademark) 2" diameter ODS C18 column eluted at 45 ml/min withwater:methanol:acetonitrile --20:15:65 for 30 minutes, then 18:17:65 for24 minutes, then 16:19:65 for 10 minutes, then 15:20:65 for 22 minutes.Fractions were collected between 44 and 48 minutes and 72 and 86minutes. Combination and evaporation of appropriate fractions gave thetitle monosaccharide (120 mg) and aglycone (5 mg) as white solids whichwere characterised by mass and nmr spectroscopy.

EXAMPLE 19 3-Cyano-5,13-dideoxy-25-cyclohexyl-22,23-dihydroavermectin B1aglycone

To a solution of 13-deoxy-25-cyclohexyl-22,23-dihydroavermectin B1aglycone (0.486 g), as described in EP-A-214731, in dry pyridine (4 ml)at 0° C. was added 2nitrobenzenesulphonylchloride (0.38 g) and mixturewas stirred for 2 hours. The pyridine was then removed and the residuewas partitioned between ether and dilute aqueous hydrochloric acid(2.5%). The organic layer was separated, washed with water, then brine,dried (MgSO₄) and evaporated to give a foam (0.43 g). The foam wasdissolved in dimethylformamide (3.7 ml) and a solution of lithiumcyanide in dimethylformamide (3.7 ml, 0.5M) added. The reaction mixturewas allowed to stand for 24 hours and then partitioned between ether andwater. The aqueous layer was separated and extracted with three portionsof ether. The combined ether extracts were dried (MgSO₄) and evaporatedto give a foam (0.3 g). The foam was taken up in ether (minimum volume)and applied to column of silica gel (60 g). After elution withether:hexane--1:2 to 1:1--combination and evaporation of appropriatefractions gave a foam (0.23 g) which was taken up in ether (minimumvolume) and applied to a column of silica gel (40 g). After elution withhexane: ether--9:1 combination and evaporation of appropriate fractionsgave a solid (65 mg) which was further purified by reverse-phase highperformance liquid chromatography on a Zorbax (trade mark) 1" diameterODS C18 column eluted with methanol:water--90:10. Combination andevaporation of appropriate fractions gave the title compound as a whitesolid which was characterised by mass and nmr spectroscopy.

EXAMPLE 20 4'-Oxo-3-cyano-5-deoxy-25-cyclohexyl,-22,23-dihydroavermectinB1 monosaccharide

To a stirred solution of3-cyano-5-deoxy-25-cyclohexyl-22,23-dihydroavermectin B1 monosaccharide(350 mg) in dichloromethane (10 ml) under an atmosphere of nitrogen atroom temperature was added powdered 4Å molecular sieves (10 mg),N-methylmorpholine oxide (350 mg) and tetra-n-propylammoniumperruthenate (35 mg). After 2 hours N-methylmorpholine oxide (175 mg),tetra-n-propylammonium perruthenate (17 mg) and powdered 4Å molecularsieves (10 mg) were added and the mixture was stirred overnight.N-methylmorpholine oxide (80 mg), tetra-n-propylammonium perruthenate (8mg were added and stirring continued for 2 hours. N-methylmorpholineoxide (80 mg), tetra-n-propylammonium perruthenate (8 mg) and powdered4Å molecular sieves (10 mg) were added and stirring continued for 2hours. The reaction mixture was then poured onto a column of silica gel(10 g) and eluted with dichloromethane. Combination and evaporation ofappropriate fractions gave the title compound (230 mg) as a colourlessglass which was characterised by mass and nmr spectroscopy.

EXAMPLE 214'-epi-Hydroxy-3-cyano-5-deoxy-25-cyclohexyl-22,23-dihydroavermectin B1monosaccharide

To a stirred solution of4'-oxo-3-cyano-5-deoxy-25-cyclonexyl-22,23-dihydroavermectin B1monosaccharide (110 mg) in methanol (2 ml) at room temperature was addedsodium borohydride (2 mg). After 30 minutes the reaction mixture waspartitioned between ether and water. The organic layer was separated,washed with water, dried (MgSO₄) and evaporated to a gum (96 mg). Theproduct was purified by reverse-phase high performance liquidchromatography on a Dynamax (trade mark) 1" diameter ODS C18 columneluted at 20 ml/min water:methanol:acetonitrile--20:15:65. Combinationand evaporation of appropriate fractions gave the title compound (50 mg)as a white solid which was characterised by mass and nmr spectroscopy.

EXAMPLE 224'-Oximino-3-cyano-5-deoxy-25-cyclohexyl-22,23-dihydroavermectin B1monosaccharide

To a stirred solution of4'-oxo-3-cyano-5-deoxy-25-cyclohexyl-22,23-dihydroavermectin B1monosaccharide (100 mg) in pyridine (2 ml) was added hydroxylaminehydrochloride (100 mg) and the mixture maintained at room temperaturefor 4 hours and then 4° C. for 48 hours. The reaction mixture was thenpartitioned between ether and water. The organic layer was separated andwashed with saturated aqueous citric acid, saturated aqueous sodiumhydrogen carbonate, water, then dried (MgSO₄) and evaporated. The crudeproduct so obtained (100 mg) was purified by reverse-phase highperformance liquid chromatography on a Dynamax (trade mark) 1" diameterODS C18 column eluted at 20 ml/min with water:methanol:acetonitrile--20:15:65. Combination and evaporation of appropriatefractions gave the title compound (13 mg) as a white solid which wascharacterised by mass and nmr spectroscopy.

EXAMPLE 234'-epi-Methylamino-4',5-dideoxy,3-cyano-25-cyclohexyl-22,23-dihydroavermectinB1 monosaccharide

To a stirred solution at room temperature of4'-oxo-3-cyano-5-deoxy-25-cyclohexyl-22,23-dihydroavermectin B1monosaccharide (0.2 g) in methanol (1 ml) containing 0.85 ml of asolution prepared by mixing methanol (10 ml), glacial acetic acid (0.7ml) and methylamine in industrial methylated spirits (1.33 ml of 33%)was added sodium cyanoborohydride (12 mg) in six equal portions over aperiod of 2 hours. A further 5 mg of sodium cyanoborohydride was addedin 3 portions during the next hour and then a further 8 mgs in oneportion. Stirring was continued for 30 minutes then the reaction mixturewas partitioned between ethyl acetate and water. The organic layer waswashed with brine. The aqueous layer was extracted with ethyl acetate.The combined organic layers were dried (MgSO₄) and evaporated to a gum(170 mg). The gum was taken up in the minimum volume of dichloromethaneand applied to a column of silica gel (40 g). Combination andevaporation of appropriate fractions obtained after elution withdichloromethane: ethyl acetate --100:0 to 0:100 gave the title compoundas a gum. The gum was dissolved in methanol (1 ml) and water (0.1 ml)added. Evaporation gave the title compound (30 mg) as a white solid.

EXAMPLE2423-Methylamino-3-cyano-5-deoxy-25-cyclohexyl-22,23-dihydroavermectin B1

To a stirred solution of 3-cyano-5-deoxy-25-cyclohexylavermectin B2 (230mg) in dichloromethane (10 ml) was added pyridinium dichromate (230 mg).After 24 hours pyridinium dichromate (230 mg) was added. After a further4 hours pyridinium dichromate (460 mg) was added and stirring continuedfor a further 24 hours. The reaction mixture was filtered andevaporated. The residue (210 mgs) was dissolved in dioxan (12 ml) andacetic acid (3.2 ml) and methoxylamine hydrochloride (70 mg) added.After 48 hours the mixture was poured into ethyl acetate (50 ml) andextracted with saturated aqueous sodium hydrogen carbonate solution,water, then dried (MgSO₄) and evaporated. The residue (120 mg) waspurified by reverse-phase high performance liquid chromatography on aDynamax (trade mark) 2" diameter ODS C18 column eluted withwater:methanol--15:85. Combination and evaporation of appropriatefractions gave the title compound (37 mg) as a white solid which wascharacterised by mass and nmr spectroscopy.

EXAMPLE 2523-Methoximino-3-cyano-5-deoxy-25-cyclohexyl-22,23-dihydroavermectin B1monosaccharide

A solution of23-methoximino-3-cyano-5-deoxy-25-cyclohexyl-22,23-dihydroavermectin B1(13 mg) in isopropanol containing 1% of sulphuric acid (0.32 ml) wasleft to stand for 24 hours. The mixture was then diluted with ether (10ml) and washed with saturated aqueous sodium hydrogen carbonatesolution, water, then dried (MgSO₄) and evaporated. The product waspurified by reverse-phase high performance liquid chromatography on aBeckmann (trade mark) 1/2 diameter ODS C18 column eluted withwater:methanol--15:85. Combination and evaporation of appropriatefractions gave the title compound (4.8 mg) as a white solid which wascharacterised by mass and nmr spectroscopy.

EXAMPLE 26 13-oxo-3-cyano-5-deoxy-25-cyclohexyl-22,23-dihydroavermectinaglycone

To a stirred solution of3-cyano-5-deoxy-25-cyclohexyl-22,23-dihydroavermectin B1 aglycone (0.8g) in dimethylformamide (30 ml) at room temperature was added pyridiniumdichromate (5 g). After 3 hours the reaction mixture was poured intowater and extracted three times with ether. The combined ether extractswere washed with water then brine. After drying over MgSO₄ andevaporating the product was purified by silica gel column chromatographyusing ether:petrol ether --1:1 as eluent. Combination and evaporation ofappropriate fractions gave the title compound (0.62 g) as a pale yellowfoam which was characterised by mass and nmr spectroscopy.

EXAMPLE 2713-Methoximino-3-cyano-5,13-dideoxy-25-cyclohexyl-22,23-dihydroavermectinB1 aglycone

A solution of methoxylamine hydrochloride (1.5 g) in water (10 ml) wasadded over 5 minutes to a stirred solution of13-oxo-3-cyano-5-deoxy-25-cyclohexyl-22,23-dihydroavermectin B1 aglycone(300 mg) in methanol (10 ml) and dioxan (20 ml). After 7 days at roomtemperature the mixture was diluted with water and extracted three timeswith ether. The combined organic layers were washed with brine, dried(MgSO₄) and evaporated. The oily residue (400 mg) was purified bychromatography on silica gel (40 g) eluted with ether:hexane--1:1 to4:1, then ether. Combination and evaporation of appropriate fractionsgave a foam (167 mg) which was further purified by reverse-phase highperformance chromatography on a Dynamax (trade mark) 1" diameter ODS C18column eluted with water: methanol--15:85. Combination and evaporationof appropriate fractions gave the title compound (90 mgs) as a whitesolid which was characterised by mass and nmr spectroscopy.

EXAMPLES 28 and 29 (E andZ)-13-Oximino-3-cyano-5,13-dideoxy-25-cyclohexyl-22,23-dihydroavermectinB1 aglycone

A solution of hydroxylamine hydrochloride (1.5 g) in water (10 ml) wasadded over 5 minutes to a stirred solution of13-oxo-3-cyano-5-deoxy-25-cyclohexyl-22,23-dihydroavermectin B1 aglycone(300 mg) in methanol (10 ml) and dioxan (20 ml). After 7 days at roomtemperature the mixture was diluted with water and extracted three timeswith ether. The combined organic layers were washed with brine, dried(MgSO₄) and evaporated. The oily residue (350 mg) was purified bychromatography on silica (40 g) eluting with ether:hexane--3:2.Combination and evaporation of suitable fractions gave a foam which wasfurther purified by reverse-phase high performance liquid chromatographyon a Dynamax (trade mark) 1" diameter ODS c18 column eluted withmethanol:water--79:21. Combination and evaporation of appropriatefractions gave the first eluted isomer of the title compound (13 mg) andsecond eluted isomer of the title compound (23 mg). Both isomers werecharacterised by their mass and nmr spectroscopy.

EXAMPLE 30 23-epi-Hydroxy-3-cyano-5-deoxy-25-cyclohexyl-avermectin B2

To a stirred solution of 3-cyano-5-deoxy-25-cyclohexylavermectin B2 (1g), phenoxyacetic acid (1.64 g) and triphenylphosphine (2.83 g) intetrahydrofuran (10 ml) at 0° C. was added diethylazodicarboxylate (1.8ml) dropwise over 5 minutes. The reaction mixture was allowed to warm toroom temperature. After 4 hours a saturated solution of ammonia inmethanol (6 ml) was added. The precipitate was filtered off, thefiltrate left overnight at room temperature and then evaporated. Theresidue was purified by column chromatography on silica gel (50 g)eluted with ether:hexane--50:50. Combination and evaporation ofappropriate fractions gave a foam which was further purified byreverse-phase high performance liquid chromatography on a Dynamax (trademark) 1" diameter ODS C18 column eluted with methanol:water--85:15.Combination and evaporation of appropriate fractions gave the titlecompound (38 mg) as a white solid which was characterised by mass andnmr spectroscopy.

EXAMPLE 31 5-Chloro-5-deoxy-25-cyclohexylavermectin B1

To a stirred solution of 25-cyclohexylavermectin B1 (5.7 g), asdescribed in EP-A-214731, in pyridine (30 ml) at 0° C. was added2-nitrobenzenesulphonyl chloride (2.85 g). After 2 hours2-nitrobenzenesulphonyl chloride (2.85 g) was added and stirringcontinued at 0° C. for 1 hour. The reaction mixture was poured intowater (250 ml) and extracted with ethyl acetate (250 ml, ×2). Thecombined organic layers were washed with dilute hydrochloric acid,saturated aqueous sodium hydrogen carbonate solution, then dried (MgSO₄)and evaporated to give the title compound as a yellow foam (6.5 g).

EXAMPLE 32 3-Cyano-5-deoxy-25-cyclohexylavermectin B1

To a stirred solution of 5-chloro-5-deoxy-25-cyclohexylavermectin B1(5.8 g) in dimethylformamide (30 ml) was added a solution of lithiumcyanide in dimethylformamide (30 ml, 0.5M). After 24 hours the reactionmixture was partitioned between ether and water. The aqueous layer wasseparated and extracted twice with ether. The combined organic layerswere washed twice with water, then brine, then dried (MgSO₄) andevaporated to give a yellow solid (5.7 g). This was purified by columnchromatography on silica gel (1Kg) eluted with hexane:ether--1:2 to 1:4.Combination and evaporation of appropriate fractions gave a foam (0.732g) which was further purified by reverse-phase high performance liquidchromatography on a Dynamax (trade mark) 2" diameter ODS C18 columneluted with water:methanol:acetonitrile--15:20:65. Combination andevaporation of appropriate fractions gave the title compound (400 mg) asa white solid which was characterised by mass and nmr spectroscopy.

EXAMPLE 33 3-Cyano-5-deoxy-25-cyclohexylavermectin B1 monosaccharide

A solution of 3-cyano-5-deoxy-25-cyclohexylavermectin B1 (70 mg) inisopropanol containing sulphuric acid (1%) (2 ml) was maintained at roomtemperature for 16 hours. The reaction mixture was diluted with etherand extracted with dilute sodium hydrogen carbonate solution. Theorganic layer was dried (Na₂ SO₄) and evaporated. The crude product (70mg) was purified by reverse-phase high performance liquid chromatographyon a Dynamax (trade mark) 1" diameter ODS C18 column eluted withmethanol:water 85:15. Combination and evaporation of appropriatefractions gave the title compound as a white solid which wascharacterised by mass and nmr spectroscopy.

EXAMPLE 343-Cyano-4",23-Diacetyl-4",5-dideoxy-22,23-dihydro-25-cyclohexylavermectinB1

To a stirred solution of 3-cyano-5-deoxy-25-cyclohexylavermectin B2 (113mg) in dichloromethane (5 ml) containing triethylamine (244 μl) at roomtemperature was added acetic anhydride (162 μl). After 1.5 hourstriethylamine (244 μl), acetic anhydride (400 μl) and4-dimethylaminopyridine (10 mgs) were added and stirring continued for afurther 22 hours. The reaction mixture was diluted with dichloromethane(100 ml) and extracted with dilute aqueous citric acid solution. Theorganic layer was separated, dried (Na₂ SO₄) and evaporated to yield agum (230 mg) which was purified by reverse phase high performancechromatography on a Dynamax (trade mark) 2" diameter ODS C18 columneluted with water and methanol (9:91). Combination and evaporation ofappropriate fraction gave the title compound as an amorphous whitepowder which was characterised by mass and nmr spectroscopy.

EXAMPLE 354'-O-Acetyl-3-cyano-5-deoxy-22,23-dihydro-25-cyclohexyl-avermectin B1monosaccharide

To a solution of 3-cyano-5-deoxy-22,23-dihydro-25-cycloavermectin B1monosaccharide (35 mg) in dichloromethane (2 ml) was added aceticanhydride (0.1 ml) and triethylamine (0.1 ml) and the mixture wasstirred at room temperature for 48 hours. The reaction mixture was thendiluted with dichloromethane (20 ml) and extracted with dilute aqueouscitric acid solution. The organic layer was separated, dried (Na₂ SO₄)and evaporated. The resultant gum was taken up in ether (2 ml) andpassed through a silica Sep-pak (trade mark). The eluate was evaporatedand the crude product was further purified by reverse-phase highperformance liquid chromatography on a Dynamax (trade mark) 1" diameterODS C18 column eluted with methanol:water 91:9. Combination andevaporation of appropriate fractions gave the title compound (11 mg) asan amorphous white powder which was characterised by mass and nmrspectroscopy.

EXAMPLE 36 3-Cyano-5-deoxy-milbemycin D

To a stirred solution of milbemycin D (2 g), as described in U.S. Pat.No. 4,346,171, in pyridine (15 ml) at 0° C. was added, in seven equalportions of 30 minutes, 2-nitrobenzenesulphonyl chloride (1.5 g). After2 hours the pyridine was evaporated and the residue partitioned betweenether and dilute hydrochloric acid. The organic layer was washed withwater, then brine, then dried (MgSO₄) and evaporated to a yellow foam(2.25 g). This was dissolved in dimethylformamide (18.5 ml) and asolution of lithium cyanide in dimethylformamide (18.5 ml, 0.5M) added.After stirring at room temperature for 24 hours the mixture waspartitioned between ether and water. The aqueous layer was separated andextracted three times with ether. The combined ether extracts were dried(MgSO₄) and evaporated to an oil (1.8 g). This was purified by columnchromatography on silica gel (400 g) eluted with ether:hexane--1:2 to2:1. Combination and evaporation of appropriate fractions gave a foamwhich was further purified by column chromatography on silica gel (50 g)eluted with ether:hexane--1:9 to 1:3. Combination and evaporation ofappropriate fractions gave upon trituration with hexane the titlecompound as a white solid which was characterised by mass and nmrspectroscopy.

EXAMPLE 37 5-Deoxy-3,4,22,23-tetrahydro-Δ²,3,4,5-25-cyclohexylavermectin B1 monosaccharide

To a stirred solution of 22,23-dihydro-25-cyclohexylavermectin B1monosaccharide (5.00 g), triphenylphosphine (3.46 g) and 4-nitrophenol(0.92 g) in anhydrous tetrahydrofuran (50 ml) at 0° C. was addeddiethylazodicarboxylate (2.3 ml). After 30 minutes triphenylphosphine(1.6 g) and diethylazodicarboxylate (2.0 ml) was added and stirringcontinued for a further 30 minutes during which time the reactionmixture was allowed to warm to room temperature.1,8-Diazobicylo[5.4.0]undec-7-ene (8 ml) was added in four equalportions over 30 minutes and the mixture then diluted with ether (500ml). The mixture was washed with aqueous citric acid (250 ml, ×2),sodium hydroxide (250 ml, 2N, ×2) and brine (250 ml, ×2). Each aqueouslayer was extracted with ether (200 ml). The combined organic layerswere washed with brine (250 ml), dried (Na₂ SO₄) and evaporated. Theresidue was purified by column chromatography on silica gel (100 g)eluted with hexane:ether--1:1 to 1:3. Combination and evaporation ofappropriate fractions gave the title compound (1.78 g) as a pale yellowsolid which was characterised by mass and nmr spectroscopy.

PREPARATION 1 13-Deoxy-25-cyclohexyl-22,23-dihydroavermectin B1 aglycone

The title compound was prepared from25-cyclohexyl-22,23-dihydroavermectin B1, described in U.S. Pat. No.5,089,480, by application of the procedures described in EP-A-002615 forthe analogous defunctionalisation at position 13 of22,23-dihydroavermectin B1a.

PREPARATION 2 13-Deoxy-23-methoxy-25-cyclohexyl-22,23-dihydroavermectinB1 glycone

The title compound was prepared from23-methoxy-25-cyclohexyl-22,23-dihydroavermectin B1, described inInternational Patent Application PCT/EP93/0036 by application of theprocedures described in EP-A-0002615 for the analogousdefunctionalisation at position 13 of 22,23-dihydroavermectin B1a.

I claim:
 1. An avermectin or milbemycin derivative, having a cyano substituent at the 3-position, a double bond at the 3-4 position and no substituent at the 5-position of the molecule.
 2. A formulation for treatment or prophylaxis of parasitic infections which comprises a compound according to claim
 1. 3. A formulation for use as an insecticide or for treating agricultural pests which comprises a compound according to claim
 1. 4. A method of treating agricultural pests which comprises applying an agricultural pest treating effective amount of a compound according to claim 1 to such pest.
 5. A compound of the formula (I): ##STR10## wherein the broken line represents an optional bond, R¹ and R⁴ being absent when this bond is present, R¹ is H, OH, C₁ -C₈ alkoxy optionally substituted by halo or by C₁ -C₄ alkoxy, C₂ -C₅ alkanoyl, C₂ -C₅ alkoxy carbonyl, carboxy, mercapto or by aryl, or R¹ is C₃ -C₈ alkenyloxy, C₂ -C₉ alkylcarbonyloxy or C₃ -C₉ alkenylcarbonyloxy, arylcarbonyl or arylcarbamoyl, said aryl optionally substituted by a C₁ -C₉ alkyl group, or R¹ is attached to the remainder of the molecule by a double bond and is oxo or oximino optionally O-substituted by a C₁ -C₈ alkyl, C₂ -C₈ alkenyl or alkynyl, trialkylsilyl or aralkyl group, or is methylene optionally substituted by a cyano or C₁ -C₉ alkyl group;R⁴ is H, OH or C₁ -C₈ alkoxy, C₁ -C₉ alkanoyloxy; ═CH₂ ; oxo or optionally substituted oximino; R² is (a) an alpha-branched C₃ -C₈ alkyl, alkenyl, alkoxy-alkyl, or alkylthioalkyl group; an alpha-branched C₄ -C₈ alkynyl group; a (C₄ -C₈)cycloalkyl-alkyl group wherein the alkyl group is an alpha-branched C₂ -C₅ alkyl group; a C₃ -C₈ cycloalkyl or C₅ -C₈ cycloalkenyl group, either of which may optionally by substituted by methylene or one or more C₁ -C₄ alkyl groups or halo atoms; or a 3 to 6 membered oxygen or sulphur containing heterocyclic ring which may be saturated, or fully or partially unsaturated and which may optionally be substituted by one or more C₁ -C₄ alkyl groups or halo atoms; or (b) a group of the formula --CH₂ R⁸ wherein R⁸ is H, C₁ -C₈ alkyl, C₂ -C₈ alkenyl, C₂ -C₈ alkynyl, alkoxyalkyl or alkylthioalkyl containing from 1 to 6 carbon atoms in each alkyl or alkoxy group, wherein any of said alkyl, alkoxy, alkenyl or alkynyl groups may be substituted by one or more halo atoms; or a C₃ -C₈ cycloalkyl or C₅ -C₈ cycloalkenyl group, either of which may optionally be substituted by methylene or one or more C₁ -C₄ alkyl groups or halo atoms; or a 3 to 6 membered oxygen or sulphur containing heterocyclic ring which may be saturated, or fully unsaturated, or partially unsaturated and which may optionally be substituted by one or more C₁ -C₄ alkyl groups or halo atoms; or a group of the formula SR⁹ wherein R⁹ is C₁ -C₈ alkyl, C₂ -C₈ alkenyl, C₃ -C₈ alkynyl, C₃ -C₈ cycloalkyl, C₅ -C₈ cycloalkenyl, phenyl or substituted phenyl wherein the substituent is C₁ -C₄ alkyl, C₁ -C₄ alkoxy or halo; or (c) a C₁ -C₆ alkyl group substituted by one oxo or one or more hydroxy groups or by a single oxygen atom on two adjacent carbon atoms forming an oxirane ring, or R² is a C₁ -C₅ alkyl group substituted by a (C₁ -C₆)alkoxy-carbonyl group, said substituents on R₂ being attached to either or both of a terminal carbon atom and a carbon atom adjacent a terminal carbon atom of R² ; or (d) ═CH₂ or a group of the formula: ##STR11## wherein R¹⁰ and R¹¹ are both H; R¹⁰ is H and R¹¹ is C₁ -C₃ alkyl, or one of R¹⁰ and R¹¹ is H and the other is phenyl, heteroaryl, C₂ -C₆ alkoxycarbonyl or substituted phenyl or heteroaryl wherein said substituent is fluorine, chlorine, C₁ -C₄ alkyl, C₁ -C₄ alkoxy, C₁ -C₄ alkylthio, hydroxy(C₁ -C₄)alkyl, cyano, aminosulphonyl, C₂ -C₆ alkanoyl, C₂ -C₆ alkoxycarbonyl, nitro, trifluoromethyl, trifluoromethoxy, amino or mono or di(C₁ -C₄)-alkylamino; and X is a direct bond or is an alkylene group having from 2 to 6 carbon atoms which may be straight or branched-chain; or (e) phenyl which may optionally be substituted with at least one substituent selected from C₁ -C₄ alkyl, C₁ -C₄ alkylthio groups, halo atoms, trifluoromethyl, and cyano;or R² may be a group of formula (II): ##STR12## wherein Z is O, S or --CH₂ -- and a, b, c and d may each independently be 0, 1 or 2; the sum of a, b, c and d not exceeding 5; R³ is hydrogen, hydroxy, C₁ -C₈ alkoxy or C₂ -C₈ alkenoxy, C₁ -C₉ alkanoyloxy or C₂ -C₉ alkenoyloxy, aroyloxy, (C₁ -C₅)alkyloxy-(C₁ -C₅)alkoxymethoxy, halogen, oxo, or optionally substituted oximino, hydrazono, carbazido or semicarbazido, N-(C₁ -C₄)alkyl semicarbazido, N,N-di(C₁ -C₄)alkylsemicarbazido, C₁ -C₅ alkanoylhydrazido, benzoylhydrazido or (C₁ -C₄)alkyl benzoylhydrazido; or R₃ is ##STR13## wherein R⁵ is attached to C-4" or C-4' by a single bond and is hydrogen, halo, hydroxy, C₁ -C₉ alkanoyloxy or C₂ -C₉ alkenoyloxy, aroyloxy, C₁ -C₈ alkoxy, amino, N-(C₁ -C₈) alkylamino, N,N-di(C₁ -C₉)alkylamino; N-(C₁ -C₅)alkanoylamino, or N,N-di(C₁ -C₉)alkanoylamino; or R⁵ is attached to C-4" or C-4' by a double bond and is oxo, oximino optionally substituted by a C₁ -C₈ alkyl, C₂ -C₈ alkenyl or alkynyl, trialkylsilyl or aralkyl group; semicarbazido, N-C₁ -C₄ alkylsemicarbazido, N,N-di (C₁ -C₄)alkyl-semicarbazido, C₁ -C₅ alkanoylhydrazido, benzoylhydrazido, or (C₁ -C₄) alkylbenzoylhydrazido; R⁶ is H or C₁ -C₆ alkyl; and R⁷ is methyl, hydroxymethyl, (C₁ -C₄ alkoxy) -methyl, (C₂ -C₅ alkanoyl)oxymethyl, (C₂ -C₅ alkenoyl) oxymethyl, aryloxymethyl, aralkanoyloxymethyl, oxo, oximino optionally substituted by a C₁ -C₈ alkyl, alkenyl, alkynyl, trialkylsilyl or aralkyl group, halomethyl, azidomethyl or cyanomethyl.
 6. A compound according to claim 5, in which R¹ is H, OH, O-(C₁ -C₄)alkyl, O-(C₁ -C₅)alkanoyl, oxo, or oximino optionally substituted by C₁ -C₄ alkyl or aryl(C₁ -C₄)alkyl.
 7. A compound according to claim 6 in which R¹ is H, OH, OCH₃, OC₂ H₅, OCOCH₃, oxo, oximino or methoximino.
 8. A compound according to claim 5, in which R¹ and R⁴ are both H.
 9. A compound according to claim 5, in which R¹ and R⁴ are absent and the optional bond is present.
 10. A compound according to claim 5, 6 or 7 in which R⁴ is H, OH, oxo or oximino.
 11. A compound according to claim 10 in which R² is straight or branched chain alkyl, alkenyl, cycloalkyl or cycloalkenyl.
 12. A compound according to claim 11 in which R² is methyl, ethyl, 2-propyl, 2-butyl, 2-buten-2-yl, 2-pentenyl, 4-methyl-2-penten-2-yl, or cyclohexyl.
 13. A compound according to claim 12, in which R⁶ and R⁷ are both methyl.
 14. A compound according to any of claims 2 to 10 in which R³ is H or of formula: ##STR14## wherein R⁵ is OH, (C₁ -C₄)alkoxy, (C₂ -C₅)alkanoyloxy, amino, N-(C₁ -C₄)-alkylamino, N-(C₁ -C₅)alkanoylamino, oxo or oximino optionally substituted by a C₁ -C₄ alkyl group.
 15. A compound according to claim 14 in which R³ is H or of formula: ##STR15## wherein R⁵ is OH, OCH₃, OC₂ H₅, OCOCH₃, methylamino, acetylamino, oxo, oximino or methoximino.
 16. A compound according to claim 2, which is:(i) 3-cyano-5-deoxy-25-cyclohexyl avermectin B2 or its monosaccharide, or (ii) 3-cyano-5-deoxy-23-methoxy-25-cyclohexyl-22,23-dihydroavermectin B1 or its monosaccharide, or (iii) 4"-oximino-3-cyano-5-deoxy-23-methoxy-25-cyclohexyl-22,23-dihydroavermectin B1; or (iv) 3-cyano-5-deoxy-25-cyclohexyl-22,23-dihydroavermectin B1 or its monosaccharide, or (v) 4'-epi-hydroxy-3-cyano-5-deoxy-25-cyclohexyl-22,23-dihydroavermectin B1 monosaccharide, or (vi) 23-methoximino-3-cyano-5-deoxy-25-cyclohexyl-22,23-dihydroavermectin B1 or its monosaccharide; or (vii) 3-cyano-5-deoxy-25-cyclohexylavermectin B1 or its monosaccharide; or (viii) 3-cyano-5,13-dideoxy-23-methoxy-25-cyclohexyl-22,23-dihydroavermectin B1 aglycone; or (ix) 3-cyano-5,13-dideoxy-25-cyclohexyl-22,23-dihydro-avermectin B1 aglycone; or (x) 3-cyano-5-deoxy-milbemycin D.
 17. The compound according to claim 16 which is 3-cyano-5-deoxy-25-cyclohexyl avermectin B2.
 18. The compound according to claim 16 which is 3-cyano-5-deoxy-25-cyclohexyl avermectin B2 monosaccharide.
 19. A formulation for treatment or prophylaxis of parasitic infections which comprises a compound according to claim
 5. 20. A formulation for use as an insecticide or for treating agricultural pests comprising a compound according to claim
 5. 21. A method of treatment or prophylaxis of parasitic infections which comprises administering to a person or animal in need of such treatment an effective antiparasitic amount of a compound according to claim
 5. 22. A method of treating agricultural pests which comprises applying an agricultural pest treating effective amount of a compound according to claim 5 to such pest.
 23. A method of treatment or prophylaxis of parasitic infections which comprises administering to a person or animal in need of such treatment an effective antiparasitic amount of a compound according to claim
 1. 24. A method of making a compound according to claim 1, which comprises allowing an avermectin or milbemycin derivative substituted at the 5-position with a leaving radical, or having no substituent at the 5-position and double bonds at the 2-3 and 4-5 positions, to react with an ionic cyanide.
 25. A method according to claim 24, in which the leaving radical is fluoro, chloro, bromo, iodo or p-nitrophenoxy.
 26. A method according to claim 24, in which an avermectin or milbemycin or derivative thereof having an --OH group at the 5-position of the molecule is converted to the corresponding derivative having a leaving radical at the 5-position and said corresponding derivative is allowed to react with an ionic cyanide without isolation of said corresponding derivative from the reaction medium.
 27. A method of making a compound according to claim 5, which comprises allowing a compound of formula (II) or (III): ##STR16## wherein R¹, R², R³, R⁴, R⁶ and R⁷ are as defined in claim 5 and X is a leaving radical to react with an ionic cyanide to make a compound of formula (I) and if necessary replacing or converting one or more of the R¹ -R⁷ substituents of the 3-cyano compound so made to produce a further compound of formula (I).
 28. A method according to claim 27 in which the leaving radical is fluoro, chloro, bromo, iodo or p-nitrophenoxy.
 29. A method according to claim 27 in which an avermectin or milbemycin or derivative thereof having an --OH group at the 5-position of the molecule is converted to the corresponding derivative having a leaving radical at the 5-position and said corresponding derivative is allowed to react with an ionic cyanide without isolation of said corresponding derivative from the reaction medium.
 30. A compound of formula (II): ##STR17## wherein R¹, R², R³, R⁴, R⁶ and R⁷ are as defined in claim
 5. 